Strand for a wire cable of synthetic wires and synthetic fibres

ABSTRACT

A wire cable strand which consists of a core of untwisted fine fibres arranged in parallel and at least two layers of course wires spirally surrounding the core, with a layer of fibre bundles arranged between these layers either sprally or parallel to the axis of the strand.

United States Patent 1191 Schmittman Oct. 22, 1974 1 1 STRAND FOR A WIRECABLE 0F [56] References Cited SYNTHETIC WIRES AND SYNTHETIC UNITEDSTATES PATENTS FIBRES 2,075,996 4/1937 Noyes 57/146 x I u 2,400,1815/1946 Warren 57/140 R 1751 Inventor figyg g gg ggi m 2.591.628 4/1952Snyder 57/140 BY 2 I 2,971,321 2/1961 Himmelfarb et a1. 57/140 R X [73]Assignee: Bayer Aktien'gesellschaft, 3.201931) 8/1952 Stirling 57/140 BYX Leverkusen, Germany I Primary ExaminerDonald E. Watkins [22] Filed"June 1973 Attorney, Agent, or FirmBurgess, 'Dinklage & [2]] App]. No.:369,690 Sprung [30] Foreign Application Priority Data 1 ABS TRACT J 79[972 German 1231968 A wire cable strand which consists of a core ofununc y twisted fine fibres arranged in parallel and at least two layersof course wires spirally surrounding the core, CCll. 57/I 35675b7/1 witha layer of fibre bundles arranged between these LM BY 46 layers eithersprally or parallel to the axis of the 57/144, 145 Strand' 14 Claims, 2Drawing Figures This invention relates to a strand for a wire cable ofsynethetic wires and synthetic fibres, comprising a core which consistsof a bundle of untwisted fine fibres arranged in parallel, a layer ofcoarse wires spirally surrounding the core, and at least one other layerof coarse wires concentrically and spirally surrounding the first layer.

Wire cables composed of such strands are used for pulling or liftingloads and for fastening goods, but they are mainly used on shipsparticularly in mooring ships in harbour. As the sizes of ship increase,so accordingly do the forces which have to be taken by mooring cables.

According to the previous state of the art it has only been possible tomanufacture wire and fibre cables with tensile strengths of up to about250 t (metric tons). If attempts are made to exceed this value, theadditional amount of material used for the cable does not result in anyutilizable increase in the strength of the cable. The cabling loss thenincreases rapidly and the specific strength or breaking length decreasesaccordingly.

lt is an object of this invention to provide a strand for wire cablesmade of synthetic wires and synthetic fibres which will be able to takemuch greaterforces, namely up to 1000 t or more and which is constructedso that the cabling loss does not increase and the specific strength andbreaking length can be kept constant, independent of the diameter of thecable.

According to the invention, this is achieved by arranging a layer offibre bundles between the layers of coarse wires. The inventiontherefore provides a strand for a wire cable which comprises a coreconsisting of a bundle of untwisted synthetic fibres, a layer of coarsesynthetic wires .spirally surrounding the core and at least one otherlayer of coarse wires concentrically and spirally surrounding the core,in which a layer of synthetic fibre bundles is arranged between thelayers of coarse wires.

This measure reduces the damaging Hertzian surface pressures which thewires exert against each other when the cable is under load. Theinvention is based on the finding that in wire cables made of syntheticfibres and synthetic wires, the cabling loss is not a function of thecable diameter but a function of the component wire section. Thedefinition that the breaking length of the cable decreases withincreasing cable diameter would be valid for synthetic wire cables onlyif the cables were geometrically identical, i.e., if the percentagecross-section or percentage tensile strength of the central core, of thestrand cores and of the wires were the same in all the cables. in fact,certain relationships exist between the percentage breaking loads of thewires and the diameter of the cable, that is to say that the cablingloss decreases with increasing proportion of the cables cores and of thelayers of fibre bundles according to the invention which serve as bufferand at the same time as load bearing elements. The breaking load of wirecables made of synthetic fibres and synthetic wires can therefore bekept constant independently of the diameter of the cable.

The materials which may be used for wires and fibres are mainlypolyamide but also include polyethylene, polypropylene, polyurethane,polyesters and polycarbonate. A strand may also be made up of wires ofdif ferent materials and, for example, the wires and fibres may be madeof different synthetic materials.

The more closely the ratio of the total thickness of the fibrous portionof a strand to the total thickness of all wires of a strand approaches agiven value, the more effectively is the transverse pressure of thewires against each other eliminated. This ratio can be expressedapproximately by the following formula:

where N is the number of wires per strand, f is the ratio of the averagespecific weight of the fibre material to the average specific weight ofthe wire material. The function V is shown in the accompanying FIG. 1for various wires in the strand.

The strand according to the invention may be produced, for example, bypassing a bundle of untwisted,

fine fibres arranged in parallel as the core of the strand through thecentre of a stranding machine and at the same time laying coarse wireswhich have no internal twist spirally around this coreat the'strandingpoint. This layer of coarse wires is surrounded by fine synthetic fibresplaced in parallel and over this is placed a second layer of coarsewires by the same method as that used for laying the first layer.Several of these strands, preferably 6 to 8, are then placed spirally,each with an internal twist, about a central fibre core to produce roundcables or joined together to form graded cables.

According to a particular embodiment of the strands according to theinvention, the fibre bundles are arranged spirally. According to anotherembodiment, the fibre bundles are arranged with their axes parallel tothe axis of the strand, and'according to a third embodiment they aredoubled and twisted. The three varia tions are equivalent and theparticular variation can in each case be selected according to themanufacturing facilities available. Fibre bundles which are arrangedspirally or with the axes of the fibres parallel to the axis of thestrand may also be doubled and twisted. In that case, any load acting onthe strand will be taken up uniformly by all the elements. According toanother embodiment, a protective twist is imparted to the fibre bundles.This method is well known and serves to facilitate the manufacturingprocess and prevent capillary splicing.

According to another, special embodiment of the invention, the coarsewires in the outermost layer at least are arranged in bundles placedspirally around a core of fibres or a wire. This construction has theadvantage that, in cables with a very large diameter, the individualwires in the layer of coarse wires can have a smaller diameter..Anotheradvantage is the resulting increased flexibility. of the cable. Inaddition, filling twine is advantageously inserted between the bundlesof coarse wires. The measure is known per 'se. It increases the strengthof the cable and, by causing the formation of a sheet of fluff, itprotects the cable against mechanical damage in use. I

According to another preferred embodiment,.filling twines are insertedin the crest of the outermost layer of wires. These serve the samefunction as the twines inserted between the bundles of coarse wires.They prevent damage to the surface of the cable and in particular damagedue to heat of friction.

FIG. 1 is a graph for the function V, defined by the equation supra, andwhich is described supra; and

FIG. 2 is an embodiment of a strand according to the invention.

An example of a strand according to the invention is illustrated theaccompanying drawings FIG. 2 and is described below. A layer 2 of coarsewires 3 is placed spirally around a core 1 which consists of a bundle ofuntwisted fine fibres arranged in parallel. This layer of coarse wires 2is surrounded by a layer 4 of fibre bundles 5. These fibre bundles 5 arearranged spirally and doubled and twisted. Round the fibre bundles 5 isa layer 6 of coarse wires 3 arranged spirally. This layer is surroundedby a layer 7 of fibre bundles 8 which are arranged parallel to the axisand have a protective twist. Lastly, this layer is surrounded by a layer9 of coarse wires 3 which are arranged in separate bundles 10 each witha core 11 of fibres. The core 11 may alternatively consist of a wire.Filling twines 12 are placed between the bundles 10 of coarse wires.Filling twines 13 are also inserted between the crests of the outermostlayer 9 of wire bundles 10. When the cable is in use, the filling twines13 are spliced open to form a sheet of fluff which protects the surfaceof the cable against damage.

EXAMPLE 1 A strand according to the embodiment illustrated in FIG. 2 iscomposed of polyamide wires and polyamide fibres. The density of thepolyamide is 1.14 g/cm. The wires have a specific strength of 48 kg/mm.The fibres have a strength per unit titre of 8.5 g/dtex.

The structure of the strand is as follows (based on FIG. 2):

325 190 dtcx fibres 10 wires each with a diameter of 2.5 mm

783 475 dtex fibres 12 wires each with a diameter of 4.5 mm

3 498 399 dtcx fibres l2 bundles each composed of 4 wires with adiameter of4 mm each and 39 070 dtcx fibre core, no filling twine.

Central layer 1 Layer of coarse wires 2 Layer 4 of fibres Layer 6 ofcoarse wires Layer 7 of fibres Layer 9 of coarse wires EXAMPLE 2 g Astrand having the construction of the example shown in FIG. 2 iscomposed of polypropylene wires and polypropylene fibres. The density ofthe polypropylene is 0.9 g/cm. The wires have a specific strength of 55kg per mm The fibres have a strength per unit titre of 6 g/dtex.

The structure of the strand is as follows (based on FIG. 2):

113 572 dtex fibres 8 wires each 2.0 mm in diameter 341 000 dtex fibres12 wires each 3.0 mm in diameter 1 246 300 dtex fibres 12 wires each 6mm in diameter and 12 filling twines each composed of 000 dtex fibres.

Core 1 Layer 2 of coarse wires Layer 4 of fibres Layer 6 of coarse wiresLayer 7 of fibres Layer 9 of coarse wires EXAMPLE 3 A strand accordingto the example shown in FIG. 2 is made up of polyester wires andpolyester fibres. The density of the polyester is 1.38 g/cm. The highstrength fibres have a strength per unit titre of 8.5 g/dtex. The wireshave a specific strength of 48 kg/mm The structure of the strand is asfollows (based on FIG. 2):

596 200 dtex fibres 10 wires each 3 mm in diameter 1 540 000 dtex fibres14 wires each 5 mm in diameter 5 313 000 dtcx fibres l6 bundles eachcontaining 4 wires 4 mm in diameter each and a fibre core of 39 070 dtexwith 4 620 dtcx filling twine in the crest of each bundle.

Core 1 Layer 2 of coarse wires Layer 4 of fibres Layer 6 of coarse wiresLayer 7 of fibres Layer 9 of coarse wires The total thickness of astrand is 22 332 dtex, made up of wir e amounting to 13 731 300 dtex andfibres amounting to 8 369 032 dtex. The compositiori of the material,based on the thickness, is therefore 62 percent of wire and 38 percentof fibres.

6 Such strands are made up into a cable which has a central core of 46101 000 dtex fibres. The cable has a weight of 8,150 g/m, a cabletensile strength of 748,312 kg and a cable breaking length of 33.6kilometers.

What we claim is:

1. A strand for a wire cable which comprises a core comprising a bundleof untwisted synthetic fibres, a layer of coarse synthetic wiresspirally surrounding the core and at least one other layer of coarsewires concentrically and spirally surrounding the core, in which a layerof synthetic fibre bundles is arranged between the layers of coarsewires.

2. A strand as claimed in claim 1 in which the core of untwisted fibresare arranged in parallel.

3. A strand as claimed in claim 1 in which the fibre bundles arearranged spirally between the layers of coarse wires.

4. A strand as claimed in claim 1 in which the fibre bundles arearranged parallel to the axis between the layers of coarse wires.

5. A strand as claimed in claim 1 in which the fibre bundles arrangedbetween the layers of coarse wires are twisted and doubled.

6. A strand as claimed in claim 1 in which the fibres bundles areprovided with a protective twist.

7. A strand as claimed in claim 1 in which the coarse wires in at leastthe outermost layer of the strand are arranged in spiral bundles eachwith a core.

8. A strand as claimed in claim 7 in which filling twines are inserted,between the bundles of coarse wires.

9. A strand as claimed in claim 7 in which filling twines are insertedbetween the crest of the outermost layer of wires.

10. A strand as claimed in claim 1, in which the wires are polyamide,polyethylene, polypropylene, polyurethane, polyester or polycarbonate,and in which the fibres are polyamide, polyethylene, polypropylene,polyurethane, polyester or polycarbonate.

11. A strand as claimed in claim 10 in which the wires and fibres aremade of polyamide.

12. A strand as claimed in claim 1 in which the wires and fibres aremade of difierent materials 13. A strand as claimed in claim 1 in whichwires are made of different materials.

14. A strand as claimed in claim 2 in which the fibre bundles arearranged spirally between the layers of coarse wires.

1. A STRAND FOR A WIRE CABLE WHICH COMPRISES A CORE COMPRISING A BUNDLEOF UNTWISTED SYNTHETIC FIBERS, A LAYER OF COARSE SYNTHETIC WIRESSPIRALLY SURROUNDING THE CORE AND AT LEAST ONE OTHER LAYER OF CORSEWIRES CONCENTRICALLY AND SPIRALLY SURROUNDING THE CORE, IN WHICH A LAYEROF SYNTHETIC FIBRE BUNDLES IS ARRANGED BETWEEN THE LAYERS OF COARSEWIRES.
 2. A strand as claimed in claim 1 in which the core of untwistedfibres are arranged in parallel.
 3. A strand as claimed in claim 1 inwhich the fibre bundles are arranged spirally between the layers ofcoarse wires.
 4. A strand as claimed in claim 1 in which the fibrebundles are arranged parallel to the axis between the layers of coarsewires.
 5. A strand as claimed in claim 1 in which the fibre bundlesarranged between the layers of coarse wires are twisted and doubled. 6.A strand as claimed in claim 1 in which the fibres bundles are providedwith a protective twist.
 7. A strand as claimed in claim 1 in which thecoarse wires in at least the outermost layer of the strand are arrangedin spiral bundles each with a core.
 8. A strand as claimed in claim 7 inwhich filling twines are inserted, between the bundles of coarse wires.9. A strand as claimed in claim 7 in which filling twines are insertedbetween the crest of the outermost layer of wires.
 10. A strand asclaimed in claim 1, in which the wires are polyamide, polyethylene,polypropylene, polyurethane, polyester or polycarbonate, and in whichthe fibres are polyamide, polyethylene, polypropylene, polyurethane,polyester or polycarbonate.
 11. A strand as claimed in claim 10 in whichthe wires and fibres are made of polyamide.
 12. A strand as claimed inclaim 1 in which the wires and fibres are made of different materials13. A strand as claimed in claim 1 in which wires are made of differentmaterials.
 14. A strand as claimed in claim 2 in which the fibre bundlesare arranged spirally between the layers of coarse wires.